Passive components today consist of a carrier with built in passive compositions usually derived from resistor or capacitor thick film technology and terminated by metal conductors. The components are mounted onto a printed wiring board (PWB) surface one at a time with pick and place equipment, and connected electrically to the circuit by one of several complex processes involving adhesives, fluxes, solder paste, and/or wave soldering or reflow.
As the demand for miniaturizing electronic devices increases, both circuit density and the density of components per unit area have dramatically increased.
The number of components has risen exponentially necessitating the shrinking of component size. Since the design of smaller, denser boards is approaching the practical limit for today's technology, circuit designers have maximized real-estate and cannot add components unless they become much smaller, or as an alternative, buried within the inner layers, i.e., vertical stacking of components.
Early versions of the embedded passive panels, as found in Japanese patent application kokoku H2-153589, had the passive components printed directly onto a metal foil. This method had drawbacks, such as adhesion problems with the resistors and low capacitance and high dissipation factor with the capacitors. The present invention achieves success with adhesion by the application of a paste underprint that was applied to the metal foil before the printing of the passive components. Therefore, the present invention utilizes an improved method of forming passive components using present cermet thick film technology for low cost embedded component formation on organic substrates.